1. Field of the Invention
The present invention relates to a probe assembly of a prober unit for testing circuits of semiconductor chips on a semiconductor wafer during fabrication of electronic devices including LSI. More particularly, the invention relates to a prober unit used for probe testing. In the probe testing, circuit terminals (i.e., pads) that are present on the semiconductor chips on the semiconductor wafer are moved into contact with probes to collectively test the electrical conductivity of the semiconductor chips at the wafer level, before the wafer is diced.
2. Description of the Related Art
As the semiconductor technology advances, highly integrated electronic devices have become more and more common. The circuit terminals (i.e., pads) on the wafer chip have also increased in number. The pads have been arranged more precisely in reduced pad areas at narrowed pad pitches.
Also in probe cards used in semiconductor circuit testing, in which the pads on the semiconductor circuits are brought into electrical connection with a probe group, the probes have been arranged more densely for increased number of pads on the semiconductor chip, reduced pad areas or narrowed pad pitches.
In a general probe card, as disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2003-075503, a narrow-pitched probe assembly is disposed at a central portion of a printed circuit board having standard, coarse-pitched lands or through holes at an outer periphery thereof to be connected to a test unit. High-density wiring near the probe assembly is connected to standard, coarse-pitched pads or through holes at an outer periphery of a common wiring board using, for example, flexible flat cables.
As another approach, a probe assembly may be fabricated using laminated multiple resin film probes as disclosed in JP-A-2007-279009. Each resin film probe includes a conductive section with a probe and an output terminal section. The conductive section is produced by etching a sheet of copper alloy foil adhering to a resin film. The output terminal sections formed on the resin films are arranged to be shifted from each other in coarse pitches when the resin film probes are laminated together. With this configuration, the output terminal sections can be connected with a printed circuit board in certain coarse pitches even in the vicinity of the probe assembly, thereby reducing the number of layers of the printed circuit boards or simplifying the wiring.
However, if the connection is established only linearly at one ends of the flexible flat cables as disclosed in JP-A-2003-075503, mounting of the probe assembly onto the printed circuit board and therefore achievement of the positional accuracy at the connecting sections may become difficult because of congestion of the flexible flat cables for further narrowed pad pitches, increased number of pins or varied pad arrangement of the semiconductor circuits.
Further, if the connection of the output terminals of the probe assembly is established only on the surface layer of the printed circuit board as disclosed in JP-A-2007-279009, the printed circuit board must include multiple layers and the resin film probes must increase in size in order for further narrowed pad pitches.
In view of the aforementioned, an object of the invention is to provide a prober unit which incorporates a probe assembly developed to correspond to narrow-pitched pad arrangements on semiconductor chips in order to solve problems regarding connection between a narrow-pitched probe assembly and coarse-pitched printed circuit boards or connection terminals of connectors. With the prober unit, testing of electrical property of narrowed pad pitches on semiconductor chips can be facilitated and the cost of the prober unit can be reduced.